Mainly, Upton’s right-handed bat helps balance a lineup that leans towards the left, and was even more tilted with the lefty Bourn. Upton, at 28, also is nearly two years younger than Bourn, who turns 30 on Dec. 27.

Upton brings much more power, almost as much speed and is considered at least as good defensively because of a stronger arm. Bourn owns a considerably better career batting average (.272 to .255) and a slim edge in OBP (.339 to .336) but those are offset by Upton’s superior slugging percentage (.422 to .365).

There also is speculation that Bourn is seeking a deal worth upwards of $100 million, which means he isn’t likely to sign anytime soon. His agent, Scott Boras, is known almost as much for stringing out negotiations as he is for scoring his clients huge deals.

But with Upton’s signing setting the bar for center fielders not named Josh Hamilton, teams could start gobbling up other free agents. Bourn, Shane Victorino and Angel Pagan top the field of center fielders after Hamilton (who might not end up in center).

A glut of corner outfielders remains on the market, too. Among those who figure to score more a multiyear deal are Nick Swisher, Ryan Ludwick, Delmon Young, Cody Ross and, possibly, Ichiro Suzuki.

Upton, meanwhile, is scheduled to be introduced by his new club at a news conference on Thursday. He had spent his entire career with the Rays’ organization after being picked second in the 2002 draft. His time in Tampa Bay, however, officially ended Wednesday afternoon when an Atlanta logo took front and center on his Twitter page.